Out of the Box Supply Chain Basic for Supply Chain Choreographer

This topic provides an overview of Out of the Box Supply Chain Basic for Supply Chain Choreographer.

This package contains Cartographer supply chains that tie together a series of Kubernetes resources that drive a developer-provided workload from source code to a Kubernetes configuration ready to be deployed to a cluster. It contains the most basic supply chains that focus on providing a quick path to deployment making no use of testing or scanning resources.

The supply chains in this package perform the following:

Building from source code:
1. Watching a Git repository, Maven repository, or local directory for changes
2. Building a container image out of the source code with Buildpacks
3. Applying operator-defined conventions to the container definition
4. Creating a deliverable object for deploying the application to a cluster
5. (Experimental) Alternatively, outputting a Carvel Package containing the application to a Git Repository
Using a prebuilt application image:
1. Applying operator-defined conventions to the container definition
2. Creating a deliverable object for deploying the application to a cluster
3. (Experimental) Alternatively, outputting a Carvel Package containing the application to a Git Repository

Prerequisites

To use this package, you must:

Install Out of the Box Templates.
Configure the Developer namespace with auxiliary objects that are used by the supply chain as described in the following section.
(Optionally) install Out of the Box Delivery Basic, if you are willing to deploy the application to the same cluster as the workload and supply chains.

Developer Namespace

The supply chains provide definitions of many of the objects that they create to transform the source code to a container image and make it available as an application in a cluster.

The developer must provide or configure particular objects in the developer namespace so that the supply chain can provide credentials and use permissions granted to a specific development team.

The objects that the developer must provide or configure include:

registries secrets: Kubernetes secrets of type kubernetes.io/dockerconfigjson that contain credentials for pushing and pulling the container images built by the supply chain and the installation of Tanzu Application Platform.
service account: The identity to be used for any interaction with the Kubernetes API made by the supply chain.
rolebinding: Grant to the identity the necessary roles for creating the resources prescribed by the supply chain.

Registries Secrets

Regardless of the supply chain that a workload goes through, there must be Kubernetes secrets in the developer namespace containing credentials for both pushing and pulling the container image that the supply chain builds when source code is provided. The developer namespace must also contain registry credentials for Kubernetes to run pods using images from the installation of Tanzu Application Platform.

Add read/write registry credentials for pushing and pulling application images:
```
tanzu secret registry add registry-credentials \
  --server REGISTRY-SERVER \
  --username REGISTRY-USERNAME \
  --password REGISTRY-PASSWORD \
  --namespace YOUR-NAMESPACE
```
Where:
- YOUR-NAMESPACE is the name you want to use for the developer namespace. For example, use default for the default namespace.
- REGISTRY-SERVER is the URL of the registry. For Docker Hub, this must be https://index.docker.io/v1/. Specifically, it must have the leading https://, the v1 path, and the trailing /. For Google Container Registry (GCR), this is gcr.io. Based on the information used in Installing the Tanzu Application Platform package and profiles, you can use the same registry server as in ootb_supply_chain_basic - registry - server.

Add a placeholder secret for gathering the credentials used for pulling container images from the installation of Tanzu Application Platform:

cat <<EOF | kubectl -n YOUR-NAMESPACE apply -f -
apiVersion: v1
kind: Secret
metadata:
  name: tap-registry
  annotations:
    secretgen.carvel.dev/image-pull-secret: ""
type: kubernetes.io/dockerconfigjson
data:
  .dockerconfigjson: e30K
EOF

With the two secrets created:

tap-registry is a placeholder secret filled indirectly by secretgen-controller Tanzu Application Platform credentials set up during the installation of Tanzu Application Platform.
registry-credentials is a secret providing credentials for the registry where application container images are pushed to.

The following section discusses setting up the identity required for the workload.

ServiceAccount

In a Kubernetes cluster, a ServiceAccount provides a way of representing an actor within the Kubernetes role-based access control (RBAC) system. In the case of a developer namespace, this represents a developer or development team.

You can directly attach secrets to the ServiceAccount through both the secrets and imagePullSecets fields. This allows you to provide indirect ways for resources to find credentials without knowing the exact name of the secrets.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: default
secrets:
  - name: registry-credentials
  - name: tap-registry
imagePullSecrets:
  - name: registry-credentials
  - name: tap-registry

Important
The ServiceAccount must have the secrets created earlier linked to it. If it does not, services like Tanzu Build Service (used in the supply chain) lack the necessary credentials for pushing the images it builds for that workload.

RoleBinding

As the supply chain takes action in the cluster on behalf of the users who created the workload, it needs permissions within Kubernetes’ RBAC system to do so.

Tanzu Application Platform v1.2 includes two ClusterRoles that describe all of the necessary permissions to grant to the service account:

workload clusterrole, providing the necessary roles for the supply chains to manage the resources prescribed by them.
deliverable clusterrole, providing the roles for deliveries to deploy to the cluster the application Kubernetes objects produced by the supply chain.

To provide those permissions to the identity you created for this workload, bind the workload ClusterRole to the ServiceAccount you created above:

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: default-permit-workload
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: workload
subjects:
  - kind: ServiceAccount
    name: default

If this is a Build cluster, and you do not intend to run the application in it, this single RoleBinding is all that’s necessary.

If you intend to also deploy the application that’s been built, bind to the same ServiceAccount the deliverable ClusterRole too:

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: default-permit-deliverable
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: deliverable
subjects:
  - kind: ServiceAccount
    name: default

For more information about authentication and authorization in Tanzu Application Platform, see Overview of Default roles for Tanzu Application Platform.

Developer workload

With the developer namespace set up with the preceding objects, such as secret, serviceaccount, and rolebinding, you can create the workload object.

To do so, use the apps plug-in from the Tanzu CLI:

tanzu apps workload create FLAGS WORKLOAD-NAME

Where:

FLAGS are the one or more flags you want to include.
WORKLOAD-NAME is the name of the workload you want to target.

Depending on what you are aiming to achieve, you can set different flags. To know more about those (including details about different features of the supply chains), see the following sections:

Building from source, for more information about different ways of creating a workload where the application is built from source code.
Using an existing image, for more information about how to use prebuilt images in the supply chains.
GitOps vs RegistryOps, for a description of the different ways of propagating the deployment configuration through external systems (Git repositories and image registries).
Carvel Package Workflow, for information about how to configure workloads to output Carvel Packages for delivery through Git repositories.